基体改进效应用于石墨炉原子吸收测定海水中铅

一般而言,现有分析方法中,除中子活化和阳极溶出伏安法外,没有任何分析技术可以直接测定海水中浓度低于5微克/升的痕量元素铅。无火焰原子吸收虽可直接测定每毫升含10~(-8)克铅,但由于海水中存在大量的碱金属和碱土金属的氯化物,在灰化过程中将导致铅的严重损失.Segar等企图借选择性挥发技术以消除海水基体干扰,但没有成功。后Robinson等应用“T”形空心原子化器测定海水中0.11微克铅/毫升。这比通常     

石墨炉原子吸收法直接测定海水中铜、镉、铅、砷

前 言 对海洋水质分析监测是进行海洋环境质量评价的基础,特别是重金属元素含量的测定,是正确评价海洋环境的必要条件。为此,研究测定海水中痕量铜、镉、铅、砷的方法,在海洋环境保护工作中有其重要的意义。 测定海水中痕量元素时,因碱金属和碱土金属的氯化物含量高,基体组成复杂,有严重的背景干扰,故国外文献报导中大多采用萃取法分离基体后进行测定,操作步骤烦琐,有机试剂有毒。用石墨炉法直接测定海水中的铜、镉、铅、砷在国内报导较少,在国外只是进行了部分工作。本文应用具有高灵敏度特点的石墨炉原子吸收光谱法,通过应用基体改进效应和改进石墨炉原子化器,排除了海水基体氯化钠和镁、钙、锶等对铜、镉、铅、砷的干扰影响,并可直接进样测定。从而省去冗长的化学预处理、萃取分离等步骤。并成功地应用于直接测定海水中的痕量铜、镉、铅、砷。方法快速、简便,适用于常规分析。     

阳极溶出伏安法连续测定底泥中的总镉和总铅

底泥样品经盐酸-硝酸-氢氟酸-高氯酸消解后，用1＋1盐酸溶解残渣，以高氯酸做支持电解质，采用阳极溶出伏安法的标准加入法，连续测定样品中的总镉和总铅。该方法测定土壤标准样品中镉和铅的相对标准偏差分别为5．6％和4．6％，相对误差分别为2．4％和-1．7％；测定自采底泥样品中镉和铅的相对偏差分别为7．7％和8．1％，方法的重复性好；测定土壤标准样品中镉加标回收率为94．0％-106．8％，铅加标回收率为95％-103．8％；自采样品中镉加标回收率为93．0％-105．6％，铅加标回收率为90．0％-105．0％，方法的准确度较高。实验中，镉和铅的半波电位稳定，峰形对称。     

石墨探针收集/石墨探针炉原子吸收法直接测定APM中痕量铅

研究一种直接收集并测定大气微粒物质中痕量有害元素铅的新方法,石墨探针直接收集ＡＰＭ后,用石墨探针炉原子吸收法直接测定收集在探针上的ＡＰＭ中痕量铅。方法特征量为４４．００ｐｇ,检出限为４８．３６ｐｇ,,相对标准偏差为３．２２％,铅学度与峰面积吸光度在０－２５０μｇ／Ｌ范围内呈线性关系,测定标准参比材料,其回收率为９４．４２％＿９９．１４％,并成功地测定了大气微粒物质中痕量铅的含量。     

催化极谱法测定海水中的铅、锌、镉

前言 测试海水中铅、锌、镉一般采用比色法、原子吸收法和阳极溶出法。我们尝试了催化极谱法在海水分析中的应用。 铅、锌、镉的吸附催化波的分别测定已有报导,但尚未报导该三元素在同一底液中的催化波,我们研究了碘化钾—硫氰酸钾—六次甲基四胺(pH=5-5.5)的底液中可同时测定铅、锌、镉。     

萃取--反萃取分离原子吸收光谱法测定海水痕量的铜锌铅镉

海水中的铜锌铅镉经氯仿乙酸丁脂萃取和硝酸反萃取得到与基体同时分离，用原子吸收光谱法分别测定反萃取液中的这四种金属。该法具有较低的检出限和较好的回收率，对海水测定可获较满意的结果。     

海水中硝酸盐氮的离子色谱分析

介绍了离子色谱法测定海水中硝酸盐氮的分析方法。该方法利用2．7mMNa2CO3＋0．3mMNaHCO3的缓冲液作为淋洗液，在方法设置的色谱条件下，测定了海水中添加硝酸盐氮标准波度分别为0．15、0．5、2．5mg/L的回收率，其结果为94.7±7．3％，变异系数为7．7％。本方法的最低检出浓度为0．05mg/L.     

石墨炉原子吸收法直接测定海岸带海水中的铜、铅、镉——以硝酸铵作为基体改进剂

一、前言 石墨炉原子吸收法的灵敏度比火焰法要高3-4个数量级,是痕量元素分析的有效方法。但是用于直接测定海水中的重金属元素首先要解决海水基体干扰的问题。海水的含盐量为2.5％-3.5％,此浓度产生的背景吸收是很高的。人们使用过多种基体改进剂来消除海水基体的干扰[1],其中最常用的改进剂是硝酸铵,它的作用是使海水中大量的NaCl基体生成易挥发的NaNO3和NH4Cl在原子化前驱除。这方面的工作已有一些报道[2·3·4]其中[2]讨论了NH4NO3消除干扰的作用,并报导了在加入NH4NO3后测定Cu。文献[3]发现加入NH4NO3测定铁、锰是不成功的,但可以测Zn。根据文献[4]报道在加入15％NH4NO3之后直接测定海水中的铅,海水需以1:1稀释。上述各报导只限于测定海水中的Cu、Pb、Zn。而且海水往往需要事先进行稀释,其原因可能是仪器扣除背景的能力不足。 本文以15％(w/v)NH4NO3作为基体改进剂,可以在同一样品中直接测定C、Pb、Cd     

横向塞曼石墨炉原子吸收法测定作物中的痕量铅

以磷酸二氢氨硝酸为基体改进剂，利用横向塞曼石墨炉原子吸收法选择最佳的灰化和原子化温度，测定作物中痕量铅，方法线性好，相关系数为0．99928。灵敏度高，准确度好。加标回标率为99．5～105％，相对标准偏差达0．74。     

萃取浓缩——原子吸收光谱测定水中痕量的铅和镉

一般地面水和海水中的铅和镉的含量都很低,基体复杂,尤其是海水中碱金属和碱土金属盐类的浓度很大,给直接喷雾测定造成很大困难。所以,大都要经过富集、浓缩、分离手续再进行原子吸收测定。富集分离方法中用得最多的是溶剂萃取法。经溶剂萃取后直接喷雾可燃性有机相进行原子吸收测定的方法不仅简便迅速,而且被测元素在甲基异丁基酮等有机相中的测定灵敏度比水溶液高。但是,     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.